Posts Tagged: Lettuce
Population explosion of insect vector contributed to $100 million in losses in 2020
While most Californians are wholeheartedly embracing the wet start to winter, one group is welcoming the rain more warily (and wearily) – lettuce growers in the Salinas Valley.
“It's a blessing, yes, we need the water,” said Tony Alameda, managing partner of Topflavor Farms, which grows a variety of produce in Monterey and San Benito counties. “But, oh gosh: with that water, here come the weeds, here comes the habitat, here comes all the other problems that go along with it.”
Weeds are overwintering havens for a tiny insect called the Western flower thrips, which in turn carries the impatiens necrotic spot virus (INSV) – a plant virus that caused $100 million in lost gross revenue for Salinas Valley growers in 2020.
The agricultural community called it “the biggest problem we've seen in a long, long time,” said Mary Zischke, facilitator of a task force convened by the Grower-Shipper Association to address INSV and a related affliction, Pythium wilt.
Widespread crop failure in 2020
Since INSV was first observed in the state in 2006, the virus – which poses no threat to people – triggered significant crop losses in 2019, leading up to a catastrophic 2020. As Alameda's lettuces began to show the telltale “bronzing” of the leaves, efforts to bag up or remove the infected plants had no effect on the virus' implacable spread.
“Nothing seemed to work,” he recalled, “and you just watch those fields collapse, week after week, until you're just like, ‘Ugh, there's nothing here to even harvest.'”
After “100% crop failure” that year in his prime fields at the heart of the Salinas Valley, Alameda tried to dodge the virus in 2021 – shifting lettuce plantings to San Benito County and instead using his most valuable land for unaffected crops such as cilantro, leeks and radishes. By decamping to San Benito, Alameda was able to harvest 70% of his usual lettuce yield.
Generally, growers enjoyed a reprieve from virus pressures in 2021. Even in this “good” year, however, about one-third of all lettuce plantings in the Salinas Valley had at least a low level of infection, according to Zischke.
“Since we were attributing a lot of our so-called good fortune – on having less damage this year – to the cooler weather, we know we can't count on that to get us out of this problem,” Zischke said. “All the models point to the fact that we're in a warming climate, so we were fortunate this year.”
More research needed on thrips
Heat waves were a major driver of the INSV disaster of 2020. Although researchers have established a link between warmer temperatures and population increases of thrips, science still has a lot to learn about those disease vectors.
“Thrips are something we're trying to understand as much as we can, but it's pretty tough because they're a little mysterious in the way they get around and where they overwinter,” said Richard Smith, a University of California Cooperative Extension vegetable crops and weed science farm advisor for the Central Coast region.
Smith – along with U.S. Department of Agriculture research entomologist Daniel Hasegawa and California State University-Monterey Bay plant pathologist JP Dundore-Arias – provided an INSV update during an Assembly agriculture committee hearing in December.
Recent studies have identified several weeds as key “reservoirs” of thrips, including malva, marestail, and hairy fleabane. The ubiquitous mustards, fortunately, appear to be poor hosts for thrips, although their pollen serve as potential food sources.
Controlling those weeds – which are beginning to spring up as the days lengthen – is a top priority during the winter months, according to Smith. Aggressive weed management in the preceding winter was an important factor in limiting the virus' spread in 2021.
And because weeds recognize no boundaries, experts are also urging managers of non-agricultural lands to keep their properties as clean as possible, including industrial sites, equipment yards and the edges of roadways – namely U.S. Route 101, which runs through the center of the valley. Some growers have been volunteering to weed their neighbors' vineyards.
“We're encouraging everybody – as best they can – to knock down known weed hosts; that's really critical,” Zischke said.
Search for long-term solutions
Within the grower community, there is “nervous optimism” for the coming year, said Alameda, as he continues to hope for an innovation that would aid in the fight against INSV – whether a more targeted pesticide application or a beneficial insect that could deter the thrips.
However, both Alameda and Zischke pointed to the breeding of more resistant lettuce varieties as the ultimate solution to INSV – albeit one that is years away.
“We have a lot of different types of lettuce that we grow, so to move resistance into all the different types of lettuce we grow throughout the season … that's going to take time,” Zischke explained.
Research funding from the state and USDA – as well as projects supported by the California Leafy Greens Research Program – can help expedite that process. But, for Alameda, the INSV crisis underscores the need for more resources and farm advisors such as Smith, who has spent more than three decades cultivating relationships and building trust within Salinas Valley communities.
Alameda would like to see a renewed focus on bringing “bright, young, passionate people who live and breathe this stuff” to the region, so growers are better equipped to handle the inevitable next calamity.
“Hopefully this is a wakeup call to all,” he said. “This is a valued industry – you have to take care of it; it cannot be taken for granted. The ‘salad bowl of the world' cannot rest on its laurels.”/h3>/h3>/h3>/h2>
How are you celebrating American agriculture in your life? In advance of National Ag Week, March 19-25, and National Ag Day, March 21, Central Valley third-grade students were “learning with lettuce” how to bring more agriculture into their lives last week. The UC Kearney Agricultural Research and Extension Center offers the free lettuce plantings every year at Farm and Nutrition Day in Fresno County and Kings County, typically around the time of National Ag Week.
Students with the help of volunteers learned how to plant tiny lettuce seedlings into a pot of healthy soil to take home for transplanting later. In addition to helping the students connect their food to agriculture, the lettuce planting offered an engaging, hands-on experience growing healthy and nutritious food at home.
National Ag Week is a nationwide effort coordinated by the Agriculture Council of America to tell the vital story of American agriculture and remind citizens that agriculture is a part of all of us. National Ag Day encourages every American to:
• Understand how food and fiber products are produced.
• Appreciate the role agriculture plays in providing safe, abundant and affordable products.
• Value the essential role of agriculture in maintaining a strong economy.
• Acknowledge and consider career opportunities in the agriculture, food and fiber industry.
Each American farmer feeds about 144 people. As the world population soars, there is even greater demand for the food, fiber and renewable resources produced in the United States. Agriculture is this nation's #1 export and incredibly important in sustaining a healthy economy. That's why National Ag Week is a great time to reflect on and be grateful for American agriculture.
The researchers are located at UC Davis; UC Agriculture and Natural Resources Research and Extension Centers; USDA research facilities in Salinas and Beltsville; California State Polytechnic University, Pomona; and the University of Arizona, Tucson.
The UC Davis-led team aims to leverage new technologies to sustain the lettuce supply, despite the challenges posed by climate change.
“We will be exploiting genomic technology to address the needs in all areas up and down the lettuce production chain,” said project leader Richard Michelmore, a plant geneticist and director of the UC Davis Genome Center.
The team's five-year renewable grant, announced recently by USDA's Specialty Crop Research Initiative funding program, was made available through the 2014 Farm Bill.
Research will range from identifying genes that are key to developing important stress-resistance traits in lettuce to fine-tuning imaging technologies that will allow growers to remotely assess the status of their crops in the field. Although grounded in plant genetics and genomics, the project also will delve into a variety of fields that are vital for ensuring sustainable production of lettuce and related leafy greens. Collaborating team members run the gamut in terms of expertise, including plant genetics and breeding, food technology, and agricultural economics.
One of the project's strengths, Michelmore said, is its longstanding collaborative relationship with large and small plant-breeding companies as well as with the California Leafy Greens Research Board, which represents growers of lettuce, spinach and other related crops.
USDA's Specialty Crop Research Initiative, which provided the project's new grant, this year awarded $50 million in grants nationwide for projects ranging from plant genetics research to new product innovation and development of new methods for responding to food safety hazards.
A new federal voucher that gives low-income women access to a range of fruits and vegetables could provide unique new marketing opportunities for California growers.
In 2009, the federal Special Supplemental Nutrition Program for Women, Infants and Children (WIC) began distributing monthly cash vouchers to low-income women with children to buy fruits and vegetables. The program reaches almost half of the infants and one-quarter of children under 5 years old in the United States.
A team of UC Cooperative Extension (UCCE) researchers and nutrition advisors has been exploring the possibility of developing a farm-to-WIC program that would link these low-income consumers with local growers. The purpose of such a program would be to increase the consumption of a wide variety of fresh produce, with a focus on locally grown produce when available.
UCCE conducted a survey of produce preferences and buying habits among WIC participants in Tulare, Alameda and Riverside counties in 2010. The full study is published in the January-March 2012 issue of California Agriculture journal.
Based on the results, the UCCE team developed a list of 19 produce items to promote in a possible new farm-to-WIC program. They are:
Although mustard greens and collards were not popular across all sites, the advisors gauged a potential market in Alameda County, so these were retained. Based on write-in responses, oranges were also added.
In California, which has the nation's largest WIC program, 82 local agencies serve about 1.43 million participants at 623 local centers, and WIC participants can redeem their monthly vouchers at 4,000 grocery stores statewide. About 40 percent shop at WIC-only stores, which stock and sell only WIC-authorized foods.
Stocking produce is relatively new to WIC-only stores; before rollout of new WIC food packages in October 2009, these stores were only required to stock limited amounts of fresh carrots. In the survey, most WIC participants (58 percent to 72.3 percent) responded that their preferred stores offered many choices, but fewer participants (18.5 percent to 41 percent) rated the produce quality as “excellent.” Key factors determining purchase decisions were produce quality and freshness, and nutrient value (vitamins and minerals). Cost was relatively less important, possibly because WIC participants procure the produce with the vouchers.
The list has served as a starting point for discussions with growers and WIC vendors.
“The survey showed that WIC participants were interested in purchasing fresh produce with better quality and more variety,” wrote lead author Lucia L. Kaiser, Cooperative Extension specialist in the UC Davis Department of Nutrition, and co-authors, in California Agriculture. “Some WIC participants that we surveyed said they avoided shopping at WIC-only stores in part because these interests were not met.”
A dish made with nopales (cactus pads).